Can a Project or Task be configured to not allow Purchase Order creation?

EBS 12.2.11

Is there any configuration in EBS that could allow a Project or Task combination to be used for Requisition and Negotiation creation but not Order creation?

The use case is that I have projects where preliminary work needs to be performed while we await formal notice-to-proceed. We know with near certainty that the project will proceed but do not want to delay requisitioning and planning activity. At the same time, we don't want buyers to generate purchase orders using specific project & task combinations until we get NTP.

I'm looking for something similar to item configuration which has a "Purchasable" flag but at the Project or Task level.